Some people will shoot me down in flames for saying it, but try ebay.
I got my 20D off there, absolutely no problems, and it arrived within 2 days. The Camera itself was in fabulous condition - I couldn't be happier.
When you buy on ebay, always pay through paypal. ebay buyer protection is very useful. This covers you for pretty much all scenarios.
When buying on ebay:
Read Feedback
Look closely at the advert ( dodgy spelling/grammar and a lack of information can be suspicious )
- Don't buy something that doesn't have photo's of it!
You should be absolutely fine if you read feedback and watch for anything dodgy. As i said, ebay buyer protection will cover you if anything happens.
Edit:
Also, look for feedback which is related specifically to the kind of thing you are buying. Always look at negative feedback first.